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Endothelial autophagy and Endothelial-to-Mesenchymal Transition (EndoMT) in eEPC treatment of ischemic AKI

View Article: PubMed Central - PubMed

ABSTRACT

Background: Autophagy enables cells to digest endogenous/exogenous waste products, thus potentially prolonging the cellular lifespan. Early endothelial progenitor cells (eEPCs) protect mice from ischemic acute kidney injury (AKI). The mid-term prognosis in AKI critically depends on vascular rarefication and interstitial fibrosis with the latter partly being induced by mesenchymal transdifferentiation of endothelial cells (EndoMT). This study aimed to determine the impact of eEPC preconditioning with different autophagy inducing agents [suberoylanilide hydroxamic acid (SAHA)/temsirolimus] in ischemic AKI.

Methods: Male C57/Bl6 N mice were subjected to bilateral renal ischemia (40 min). Animals were injected with either untreated, or SAHA- or temsirolimus-pretreated syngeneic murine eEPCs at the time of reperfusion. Mice were analyzed 48 h and 4 weeks later. In addition, cultured eEPCs were treated with transforming growth factor (TGF)-β ± SAHA, autophagy (perinuclear LC3-II), and stress-induced premature senescence (SIPS—senescence-associated β-galactosidase, SA-β-Gal), and were evaluated 96 h later.

Results: Cultured eEPCs showed reduced perinuclear density of LC3-II + vesicles and elevated levels of SA-β-Gal after treatment with TGF-β alone, indicating impaired autophagy and aggravated SIPS. These effects were completely abrogated by SAHA. Systemic administration of either SAHA or tems pretreated eEPCs resulted in elevated intrarenal endothelial p62 at 48 h and 4 weeks, indicating stimulated endothelial autophagy. This effect was most pronounced after injection of SAHA-treated eEPCs. At 4 weeks endothelial expression of mesenchymal alpha-smooth muscle actin (αSMA) was reduced in animals receiving untreated and SAHA-pretreated cells. In addition, SAHA-treated cells reduced fibrosis at week 4. Tems in contrast aggravated EndoMT. Postischemic renal function declined after renal ischemia and remained unaffected in all experimental cell treatment groups.

Conclusion: In ischemic AKI, intrarenal endothelial autophagy may be stabilized by systemic administration of pharmacologically preconditioned eEPCs. Early EPCs can reduce postischemic EndoMT and fibrosis in the mid-term. Autophagy induction in eEPCs either increases or decreases the mesenchymal properties of intrarenal endothelial cells, depending on the substance being used. Thus, endothelial autophagy induction in ischemic AKI, mediated by eEPCs is not a renoprotective event per se.

No MeSH data available.


Related in: MedlinePlus

Postischemic kidney function in all experimental groups. Ischemia diminished excretory function until week four. Cell therapy did not improve serum creatinine levels with one exception (native eEPCs at 48 h) (Data are mean ± SEM, ‘*’ indicates significant differences (p < 0.05) as compared to untreated controls, ‘#’ indicates differences as compared to the ‘IRI’-group–for exact p-values, see text)
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Fig3: Postischemic kidney function in all experimental groups. Ischemia diminished excretory function until week four. Cell therapy did not improve serum creatinine levels with one exception (native eEPCs at 48 h) (Data are mean ± SEM, ‘*’ indicates significant differences (p < 0.05) as compared to untreated controls, ‘#’ indicates differences as compared to the ‘IRI’-group–for exact p-values, see text)

Mentions: Excretory kidney function was significantly affected in all postischemic mice. At 48 h (serum creatinine in mg/dl): Control 0.28 ± 0.01, IRI 0.59 ± 0.03, IRI+eEPCs 0.49 ± 0.02, IRI+eEPCs+SAHA 0.58 ± 0.02, IRI+eEPCs+temsirolimus 0.49 ± 0.03. At 4 weeks: IRI 0.47 ± 0.02, IRI+eEPCs 0.47 ± 0.02, IRI+eEPCs+SAHA 0.5 ± 0, IRI+eEPCs+temsirolimus 0.47 ± 0.01. The p-values were: Control vs. IRI 48 h (p < 0.0001) vs. IRI+eEPCs 48 h (p < 0.00t01) vs. IRI+eEPCs+SAHA 48 h (p < 0.0001) vs. IRI+eEPCs+temsirolimus 48 h (p = 0.00053) vs. IRI 4 weeks (p < 0.0001) vs. IRI+eEPCs 4 weeks (p < 0.0001) vs. IRI+eEPCs+SAHA 4 weeks (p < 0.0001) vs. IRI+eEPCs+temsirolimus 4 weeks (p < 0.0053). Finally, administration of unconditioned and temsirolimus pretreated eEPCs improved kidney function at 48 h: IRI vs. IRI+eEPCs (p = 0.019) vs. IRI+eEPCs+temsirolimus (p = 0.037) (Fig. 3).Fig. 3


Endothelial autophagy and Endothelial-to-Mesenchymal Transition (EndoMT) in eEPC treatment of ischemic AKI
Postischemic kidney function in all experimental groups. Ischemia diminished excretory function until week four. Cell therapy did not improve serum creatinine levels with one exception (native eEPCs at 48 h) (Data are mean ± SEM, ‘*’ indicates significant differences (p < 0.05) as compared to untreated controls, ‘#’ indicates differences as compared to the ‘IRI’-group–for exact p-values, see text)
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getmorefigures.php?uid=PMC5016542&req=5

Fig3: Postischemic kidney function in all experimental groups. Ischemia diminished excretory function until week four. Cell therapy did not improve serum creatinine levels with one exception (native eEPCs at 48 h) (Data are mean ± SEM, ‘*’ indicates significant differences (p < 0.05) as compared to untreated controls, ‘#’ indicates differences as compared to the ‘IRI’-group–for exact p-values, see text)
Mentions: Excretory kidney function was significantly affected in all postischemic mice. At 48 h (serum creatinine in mg/dl): Control 0.28 ± 0.01, IRI 0.59 ± 0.03, IRI+eEPCs 0.49 ± 0.02, IRI+eEPCs+SAHA 0.58 ± 0.02, IRI+eEPCs+temsirolimus 0.49 ± 0.03. At 4 weeks: IRI 0.47 ± 0.02, IRI+eEPCs 0.47 ± 0.02, IRI+eEPCs+SAHA 0.5 ± 0, IRI+eEPCs+temsirolimus 0.47 ± 0.01. The p-values were: Control vs. IRI 48 h (p < 0.0001) vs. IRI+eEPCs 48 h (p < 0.00t01) vs. IRI+eEPCs+SAHA 48 h (p < 0.0001) vs. IRI+eEPCs+temsirolimus 48 h (p = 0.00053) vs. IRI 4 weeks (p < 0.0001) vs. IRI+eEPCs 4 weeks (p < 0.0001) vs. IRI+eEPCs+SAHA 4 weeks (p < 0.0001) vs. IRI+eEPCs+temsirolimus 4 weeks (p < 0.0053). Finally, administration of unconditioned and temsirolimus pretreated eEPCs improved kidney function at 48 h: IRI vs. IRI+eEPCs (p = 0.019) vs. IRI+eEPCs+temsirolimus (p = 0.037) (Fig. 3).Fig. 3

View Article: PubMed Central - PubMed

ABSTRACT

Background: Autophagy enables cells to digest endogenous/exogenous waste products, thus potentially prolonging the cellular lifespan. Early endothelial progenitor cells (eEPCs) protect mice from ischemic acute kidney injury (AKI). The mid-term prognosis in AKI critically depends on vascular rarefication and interstitial fibrosis with the latter partly being induced by mesenchymal transdifferentiation of endothelial cells (EndoMT). This study aimed to determine the impact of eEPC preconditioning with different autophagy inducing agents [suberoylanilide hydroxamic acid (SAHA)/temsirolimus] in ischemic AKI.

Methods: Male C57/Bl6&nbsp;N mice were subjected to bilateral renal ischemia (40&nbsp;min). Animals were injected with either untreated, or SAHA- or temsirolimus-pretreated syngeneic murine eEPCs at the time of reperfusion. Mice were analyzed 48&nbsp;h and 4&nbsp;weeks later. In addition, cultured eEPCs were treated with transforming growth factor (TGF)-&beta;&nbsp;&plusmn;&nbsp;SAHA, autophagy (perinuclear LC3-II), and stress-induced premature senescence (SIPS&mdash;senescence-associated &beta;-galactosidase, SA-&beta;-Gal), and were evaluated 96&nbsp;h later.

Results: Cultured eEPCs showed reduced perinuclear density of LC3-II&nbsp;+&nbsp;vesicles and elevated levels of SA-&beta;-Gal after treatment with TGF-&beta; alone, indicating impaired autophagy and aggravated SIPS. These effects were completely abrogated by SAHA. Systemic administration of either SAHA or tems pretreated eEPCs resulted in elevated intrarenal endothelial p62 at 48&nbsp;h and 4&nbsp;weeks, indicating stimulated endothelial autophagy. This effect was most pronounced after injection of SAHA-treated eEPCs. At 4&nbsp;weeks endothelial expression of mesenchymal alpha-smooth muscle actin (&alpha;SMA) was reduced in animals receiving untreated and SAHA-pretreated cells. In addition, SAHA-treated cells reduced fibrosis at week 4. Tems in contrast aggravated EndoMT. Postischemic renal function declined after renal ischemia and remained unaffected in all experimental cell treatment groups.

Conclusion: In ischemic AKI, intrarenal endothelial autophagy may be stabilized by systemic administration of pharmacologically preconditioned eEPCs. Early EPCs can reduce postischemic EndoMT and fibrosis in the mid-term. Autophagy induction in eEPCs either increases or decreases the mesenchymal properties of intrarenal endothelial cells, depending on the substance being used. Thus, endothelial autophagy induction in ischemic AKI, mediated by eEPCs is not a renoprotective event per se.

No MeSH data available.


Related in: MedlinePlus